Recyclable plastic label

ABSTRACT

The disclosure relates to a mechanically recyclable label (1) comprising a face (2) and an adhesive (4). The face (2) comprises ethylene containing polymer and the adhesive (4) comprises pressure sensitive adhesive. The pressure sensitive adhesive comprises at least 15 wt. % of a base polymer, at least 25 wt. % of a tackifier and at least 10 wt. % of a plasticizer. The base polymer, the tackifier and the plasticizer are colourless and odourless. The base polymer is a polyolefin. The mechanically recyclable label (1) is mechanically recyclable with packaging material comprising ethylene containing polymer. The disclosure further relates to a label laminate (8), a method for manufacturing a label laminate (8), a labelled item (101), as well as to use of a label (1) and of a label laminate (8). The disclosure also relates to use of a waste matrix of the label laminate for producing granulates of recycled plastic.

TECHNICAL FIELD

This specification relates to a recyclable label and a label laminatefor providing recyclable labels. In particular, the specificationrelates to a mechanically recyclable label and a label laminate forproviding the same.

BACKGROUND

It is a general practice to apply a label to the surface of containersor other packages to provide decoration, identification and/orinformation, for example, on the contents of the container or otherpackage. The use of polymer containers or packages has been increasing.

Packaging materials based on plastic materials, for example PE, aremechanically recyclable. Mechanical recyclability of a specific productis determined by the recyclability of the different components of apackaging and their combination in a specific recycling stream. Beforebeing able to determine the recyclability of a specific packaging, therecyclability of each of the components needs to be assessed. Mechanicalrecycling places stricter demands on the contents of the recyclingstream when compared to chemical recycling, which is a process wherein apolymer is broken to its original monomer form so that it can eventuallybe processed (re-polymerized) and remade into new materials. However,mechanical recycling process may be more efficient in terms of energyand chemicals consumption when compared to the chemical one.

It would be desirable to produce labels which may be mechanicallyrecycled together with the packaging materials without compromising thequality of the recycled fraction. It may be rather straightforward tochoose a label face/substrate material(s) that is/are compatible withthe packaging material in terms of recyclability. However,incompatibility issues are most likely to be caused by the adhesive(s)that is/are used as a part of the label structure. Such adhesives mayinclude the lamination adhesive for combining the substrate layers in amultilayer label structure into a single laminated face structure, orthe pressure sensitive adhesive for providing the adhesion of mono- ormultilayer label face material to the labelled item. The incompatibilityissues may be more pronounced with the pressure sensitive adhesives astheir formulation to achieve all desired properties such as anchorage,shear resistance, tack, peel strength etc. is complicated and requiresseveral different components to be properly balanced with each other.Most of the adhesives used in labels cannot be washed away or otherwiseremoved before recycling, and thus they typically end up into therecycling process and may be responsible for lowering the quality of therecycled fraction.

SUMMARY

It is an aim of this specification to provide a mechanically recyclablelabel that does not compromise quality of the recycled fraction, inother words a label that shows recycling compatibility. Particularly,aim is to provide a label comprising an adhesive that does notcompromise quality of the recycled fraction. Most importantly, theadhesive components are chosen such that they are chemically compatiblewith each other as well as with the packaging material.

According to an embodiment, a mechanically recyclable label comprising aface and an adhesive is provided. The face comprises ethylene containingpolymer. The adhesive comprises pressure sensitive adhesive. Thepressure sensitive adhesive comprises at least 15 wt. % of a basepolymer, at least 25 wt. % of a tackifier and at least 10 wt. % of aplasticizer. The base polymer, the tackifier and the plasticizer arecolourless and odourless. The base polymer is a polyolefin. Themechanically recyclable label is mechanically recyclable with packagingmaterial comprising ethylene containing polymer.

According to an embodiment, a label laminate for providing mechanicallyrecyclable labels is provided. The label laminate comprises a face, anadhesive and a release liner. The face is adjoined to the release linervia the adhesive. The face comprises ethylene containing polymer and theadhesive comprises pressure sensitive adhesive. The pressure sensitiveadhesive comprises at least 15 wt. % of a base polymer, at least 25 wt.% of a tackifier and at least 10 wt. % of a plasticizer. The basepolymer, the tackifier and the plasticizer are colourless and odourless.The base polymer is a polyolefin. The mechanically recyclable label ismechanically recyclable with packaging material comprising ethylenecontaining polymer.

According to an embodiment, a method for manufacturing a label laminateis provided. The method comprises the following steps of:

-   -   arranging a substrate as a release liner or a face,    -   coating the substrate with an adhesive, the adhesive comprising        pressure sensitive adhesive, and    -   laminating the release liner together with the face in such a        way that the adhesive is arranged in between the face and the        release liner.

The face comprises ethylene containing polymer and the pressuresensitive adhesive comprises at least 15 wt. % of a base polymer, atleast 25 wt. % of a tackifier and at least 10 wt. % of a plasticizer.The base polymer, the tackifier and the plasticizer are colourless andodourless, and the base polymer is a polyolefin.

According to an embodiment, a labelled item comprising an item and amechanically recyclable label as described herein is provided. Themechanically recyclable label is attached to a surface of the itemthrough the adhesive of the label.

According to an embodiment, use of a mechanically recyclable labeldescribed herein for labelling an item is provided.

According to an embodiment, use of a label laminate described herein forproviding mechanically recyclable labels is provided.

According to an embodiment, use of a waste matrix of a label laminatedisclosed herein for producing granulates of recycled plastic isprovided. The waste matrix comprises a face and an adhesive.

According to an embodiment, a granulate of recycled plastic is provided.The granulate comprises a waste matrix of a label laminate disclosedherein. The waste matrix comprises a face and an adhesive.

According to an embodiment, a use of a granulate disclosed herein forproviding a plastic item is provided.

According to an embodiment, a plastic item comprising a granulate ofrecycled plastic disclosed herein is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates, by way of an example, a 3D view of a label accordingto an embodiment,

FIG. 2 illustrates, by way of an example, a cross sectional view of cutlabels attached to a common release liner,

FIG. 3 illustrates, by way of an example, a label attached to an item,

FIG. 4 illustrates, by way of an example, a mechanical recycling processfor recycling of plastic,

FIG. 5 illustrates optical microscopy images of test experiments showingcompatibility of different types of commercially available adhesiveswith PE, and

FIG. 6 illustrates optical microscopy images of test experiments showingcompatibility of different components of hot melt adhesive with PE.

The figures are schematic. The figures are not in a particular scale.

DETAILED DESCRIPTION

The solution is described in the following in more detail with referenceto some embodiments, which shall not be regarded as limiting.

In this description and claims, the percentage values relating to anamount of a material are percentages by weight (wt. %) unless otherwiseindicated. Term “comprising” may be used as an open term, but it alsocomprises the closed term “consisting of”. Unit of temperature expressedas degrees C. corresponds to ° C. Following reference numbers anddenotations are used in this specification:

-   DSC differential scanning calorimetry-   MRK1 graphics-   MW molecular weight-   PIB polyisobutylene-   Sx, Sy, Sz 3D coordinates-   1 a (mechanically recyclable) label-   2 a face-   4 an adhesive-   6 a release liner-   8 a label laminate-   10 a backing material-   12 a release layer-   100 an item-   101 a labelled item-   421 a pre-treatment step-   422 a heating and mixing step-   423 a pelletizing step

Within context of this description, term “polymer” includes bothconventional homopolymers, that is, homogeneous polymers prepared from asingle monomer, and copolymers, meaning polymers prepared by a reactionof at least two monomers or otherwise containing chemicallydifferentiated segments or blocks therein even if formed from a singlemonomer.

A label is a piece of material to be applied onto articles of differentshapes and materials. An article may be a package. A label comprises atleast a face material also referred to as a face stock or a face. Atypical way to adhere the label onto an article is by use of adhesive.The label comprising an adhesive layer is referred to as an adhesivelabel. The adhesive may comprise pressure sensitive adhesive (PSA). Alabel comprising pressure sensitive adhesive may be referred to as apressure sensitive adhesive label. Pressure sensitive adhesive labelsmay also be referred to as self-adhesive labels.

The labels comprising PSA can be adhered to most surfaces through anadhesive layer without the use of a secondary agent, such as a solvent,or heat to strengthen the bond. The PSA forms a bond when pressure isapplied onto the label at ambient temperature (e.g. between 15 and 35°C.) or for cold applications even under freezing temperatures below 0°C., adhering the label to the item to be labelled. Examples of pressuresensitive adhesives include water-based (water-borne) PSAs, solventbased PSAs and hot-melt PSAs. A label may further comprise otheradhesive(s).

Face refers to a top substrate of the label, also called as a face stockor a face material. In case of a plastic face material it may also becalled a face film. The face may have a monolayer or multilayerstructure comprising at least two layers. These layers may be formed andcombined together through a coextrusion process or the pre-existinglayers may be laminated together into a multilayer structure usinglamination adhesive or adhesives. The face is the layer that is adheredto the surface of an article during labelling through an adhesive layer,typically pressure sensitive adhesive layer. The face comprises anadhesive side and a print side. A combination comprising a face and anadhesive may be referred to as an adhesive label. The face may comprisee.g. print in order to provide information and/or visual effect.Printable face is suitable for printing by any of the known printingmethods, such as with gravure, flexographic process, offset, screen orletter-press. The printing may exist on a top surface, reverse side orboth top and reverse side of the face. Further, the label may containadditional layers, for example top coatings or overlaminates to protectthe top surface and/or print of the label against rubbing or otherexternal stress. Coating or additional layers, such as a primer, mayenable enhancing compatibility of adjacent layers or parts of the label,for example adhesion between the layers. The primer may also act as abarrier preventing adhesive components from migrating into the face. Alabel comprising a face, a print layer and an adhesive may be referredto as a printed label.

Release liner refers to a structure comprising a substrate and a releaselayer on a surface of the substrate contacting the adhesive in a labellaminate. The substrate may also be called a backing material. Therelease liner may comprise a release coating. The release coating maycomprise a release agent, for example a silicone or non-silicone basedagent. The release agent is a chemical having low surface tension. Therelease agent may be used in order to prevent other materials frombonding to it and to provide a release effect.

The release coating provides a non-adherent surface i.e. low adhesionand release effect against the adhesive. Release liners of the labellaminates may serve one or more useful functions: they may be used as acarrier sheet onto which the adhesive is coated; they may protect theadhesive layer during storage and transportation; they may provide asupport for labels during diecutting and printing, and ultimately theymay provide the release substrate carrying the labels for dispensingonto the items to be labelled. Release liner allows for efficienthandling of individual labels after the labels are die-cut and thesurrounding matrix is stripped up to the point wherein the individuallabels are dispensed on a labelling line. During dispensing the releaseliner is peeled off and discarded.

Label laminate, also referred to as an adhesive label laminate refers toa product comprising a mono- or multilayer face, adhesive and a releaseliner. In the label laminate the face is laminated together with therelease liner having the adhesive in between, this adhesive typicallybeing a pressure sensitive adhesive. The label face material may beitself a laminated structure with several face layers laminated togetherwith lamination adhesive(s). The label laminate may be a continuousstructure from which the individual labels may be die-cut. The releaseliner of the label laminate is typically removed prior to labelling i.e.attaching the label onto the surface of an item to be labelled.

The manufacturing process of label laminates and labels thereoftypically comprises steps of providing a face stock and a release liner,applying an adhesive layer onto a surface of the face stock and/or ontoa surface of the release liner and laminating the face stock with therelease liner in such a way that the adhesive layer is arranged inbetween the face stock and the release liner in order to form a labellaminate.

The label laminate may be converted, i.e. individual labels may be cutfrom the label laminate structure. After cutting, the labels may remainto be attached to a common release liner (i.e. the release liner remainsuncut). Thus, a plurality of labels may remain to be attached to acommon continuous release liner. This may be called a converted labelweb. Alternatively, the labels may be completely separate (i.e. also therelease liner may be cut).

In the lamination process so-called machine rolls, the width of therolls corresponding to the width of the manufacturing/laminatingmachine, are typically formed. The machine rolls may be slit, i.e. cutlengthwise to so-called customer rolls with smaller widths. The slittinginvolves typically unwinding the machine roll, then slitting the web andagain winding the narrower webs into individual customer rolls.Alternatively, the slitting into customer rolls may be performed as apart of the label lamination process as an in-line process, or it mayeven be performed as part of the label laminate converting process,wherein the label laminate is die-cut (kiss cut) to form individuallabels carried by continuous release liner.

The label may also be a so-called linerless label. The linerless labelcomprises a mono- or multilayer face and an adhesive on the face.Alternatively the label may be a so-called shrink label, where heatshrinkable polymeric face material(s) are seamed and rolled on orsleeved around labelled articles and shrunk around the items. Shrinkablelabels may comprise additionally some pressure sensitive adhesive(s) orthose may be produced completely without pressure sensitive adhesive, oreven without seaming adhesive.

Labels may be used in wide variety of labelling applications and end-useareas, such as labelling of food, home and personal care products,industrial products, pharmaceutical and health care products, beverageand wine bottles, other consumables etc. Labels enable providinginformation, like product specification, on the labelled product(s).Information, e.g. print of a label, may comprise human-readableinformation, like image(s), logo(s), text, and/or machine-readableinformation, like bar code(s), QR (Quick Response) code(s).

This specification aims to provide a label that is mechanicallyrecyclable together with a packaging material the label has been adheredto. Aim is to provide a label that does not compromise quality of therecycled fraction. Particularly, aim is to provide a label comprising anadhesive that does not compromise quality of the recycled fraction. Mostimportantly, chemical compatibility of the adhesive components with eachother as well as with the packaging material must be assured. Mixingchemically incompatible components may cause different phases to form,which may be visually detected by increased haze of the material.

Besides chemical compatibility, the label and thus also the adhesivetherein must show recycling compatibility, meaning that they do notcompromise quality of the recycled fraction. Quality of the recycledfraction may refer to odour, colour, processability, mechanicalproperties, and/or optical properties. “Not compromising the quality”means that the recycled plastic material is not substantially of lowerquality in terms of, for example, odour, colour, processability,mechanical properties and/or optical properties, when compared torecycled plastic material wherefrom the label (and the adhesive therein)has been removed before recycling. Thus, the label to be recycled shouldnot cause lowering of the quality of the recycled plastic material.

Label Structure

Referring to FIG. 1 a label 1, within context of this specification amechanically recyclable label, comprises a face 2 and an adhesive 4. Thelabel is attachable to an item 100 through the adhesive 4. Further thelabel 1 typically includes graphical patterns (graphics) MRK1 on itsface 2. During label manufacturing, continuous face 2 may be laminatedtogether with a release liner 6 having the adhesive 4 in between so asto provide a label laminate 8 from which the individual labels 1 can becut. Term “label laminate” 8, within context of this specification alabel laminate for providing mechanically recyclable labels, refers to acontinuous structure comprising a face 2, an adhesive 4 and a releaseliner 6. Individual labels 1 may be die-cut from the continuous labellaminate 8. A label laminate 8 illustrated in FIG. 2 comprises four cutlabels 1 attached to a common release liner 6. The release liner 6 has abacking material 10 coated with a release layer 12. During labelling therelease liner 6 is removed and the label 1 is attached onto a surface tobe labelled through the adhesive.

FIG. 2 presents an example embodiment of a label laminate 8 comprisingfour cut labels 1 attached to a common release liner 6. The labellaminate structure may comprise a face 2, a release liner 6 and anadhesive 4. The adhesive 4 is arranged between a release layer 12 of therelease liner 6 and the face 2. Referring to FIG. 1 , the labelstructure may further comprise printing as graphics MRK1. A top surfaceof the face 2 may be printed. The printing may be subsequently topcoated in order to protect the printing. Alternatively, or in addition,the reverse side of the face 2, adjacent to the adhesive 4, may beprinted so that this print is visible through transparent adhesive layer4 when release liner 6 is attached and label is not yet dispensed ontoan article or is removed from the article. In some embodiments, theadhesive layer 4 may also be printable.

The label 1 may further comprise a primer layer. The primer layer may bearranged in between the face 2 and the adhesive 4.

Face

Within context of this specification, the face 2 comprises ethylenecontaining polymer. The ethylene containing polymer refers to a polymerthat comprises ethylene as a monomer unit. The ethylene containingpolymer may refer to polyethylene, copolymer containing ethylene, orpolyethylene mixed with other polymer.

The face 2 may comprise polyethylene (PE). Polyethylene may also becalled polyethene. The term “polyethylene” may include homopolymers ofethylene and copolymers of ethylene and one or more C₃₋₈ alpha-olefins.Copolymers of ethylene and one or more C₃₋₈ alpha-olefins may compriseat least 50 mol-% of ethylene. Polyethylene may be low densitypolyethylene (LDPE). LDPE may typically be defined by having a densityof between 0.910-0.940 g/cm³. Polyethylene may be high densitypolyethylene (HDPE). HDPE may typically be defined by having a densityof greater than or equal to 0.941 g/cm³. Medium density polyethylene(MDPE) may typically be defined having a density of between 0.926-0.940g/cm³. Polyethylene may be linear low density polyethylene (LLDPE),ultra-low density polyethylene (ULDPE) or metallocene linear low densitypolyethylene (MLLDPE). Due to their characteristic manufacturingprocess, LLDPE and HDPE may in particular be utilized in oriented filmicmaterials.

The face 2 may be a single layer structure or it may comprise multiplelayers, for example three layers. At least one, preferably all layers ofthe multiple layered face comprises ethylene containing polymer.

Adhesive

A label 1 can be affixed to the surface of an item 100 through anadhesive 4 so as to form a labelled item 101, as illustrated in FIG. 3 .Adhesive 4 provides adhesion, i.e. adheres or bonds the label 1 to thesurface of the item 100. The adhesive 4 of the label 1 should have asuitable adhesion, i.e. tack (stickiness) in order to stick to an item100 during labelling process. Tack is the property adhesive that allowsthe immediate formation of a bond on contact with another surface.Tackiness is needed at the point the label is attached to an item 100.The optimum adhesion between two materials depends on, for example,wetting and surface energy of the materials.

An adhesive 4 may be a continuous coating covering 100% of the facesurface. Alternatively, it may be arranged discontinuously as spots orstrips covering less than 100% of the face surface. This may be called“pattern gumming”. For example, the adhesive may cover between 10 to 90%of the total area of the face 2. Reduced amount of adhesive may haveeffect on recyclability of the label, as incompatibility issues causedby the adhesive may be diminished by the smaller amount of the adhesivecomprised by the label.

An adhesive 4 may have a thickness in the range of about 5-40 μm, or inthe range of about 5-20 μm. For example, the thickness of the adhesiveis in the range of about 10-20 μm or 15-20 μm. A coat weight of theadhesive, in dry weight, may be in the range of about 5-40 g/m², or 5-20g/m². The coat weight of the adhesive may be preferably less than 25g/m², or equal or less than 20 g/m². For example, the coat weight of theadhesive is between 10 and 20 g/m² or between 15 and 20 g/m².

As a rule of thumb, the adhesive coating thickness is related to thecoat weight of the adhesive in such a way, that generally coat weight of1 g/m² corresponds to coating thickness of ˜1 μm or slightly less.

Herein, an adhesive 4 adjacent to the surface of the item labelledcomprises a pressure sensitive adhesive(s) (PSA). PSA is a type of anadhesive which forms a bond when pressure is applied in order to bondthe adhesive with an adherend. The adhesive may be pressure sensitive assuch or it may be activatable in order to be pressure sensitive. Anexample is hot melt PSA, which typically comprises high-viscositymaterials that may be heated to reduce viscosity enough in order toallow coating, and then cooled to their final form. Further examplesinclude water-based and solvent-based adhesives. All of said adhesivecategories may comprise the components described below.

Especially in shrink labels adhesive may be present solely on a leadingand/or trailing edge of a label for adhering the label edges to thesurface to be labelled.

In labels comprising a multi-layered face, adhesive may be presentbetween the separate layers of the face for adhering the layers to eachother.

Adhesive may be rubber-based. Rubber-based adhesives can either comprisesynthetic rubber or natural rubber. Rubber-based adhesives typicallycontain at least one tackifier resin and/or one plasticizer becauserubber is not usually fundamentally tacky. Rubber-based adhesivestypically have good adhesion to non-polar substrates such as untreatedpolyethylene and polypropylene.

Adhesive may comprise thermoplastic elastomer, such as styrene blockcopolymer or polyolefin.

Adhesive may be styrene block copolymer-based. Styrene blockcopolymer-based means that the base polymer of the adhesive belongs tostyrene block copolymers.

Adhesive may be polyolefin-based. Polyolefin-based means that the basepolymer of the adhesive composition belongs to polyolefins. Polyolefinis a type of a polymer produced from a simple olefin, i.e. alkene withthe general formula of C_(n)H_(2n), as a monomer. Within context of thisspecification, suitable monomers of polyolefins comprise for exampleethylene, propylene, 1-butene, octene, hexene. Polyolefin-based adhesivemay comprise copolymer(s) of ethylene, propylene, 1-butene, octene,hexene. Polyolefins may be functionalized for example with oxygencontaining monomer(s). Polyolefins may comprise one or more monomers.

Polyolefins may be produced using Ziegler-Natta catalysis ormetallocene, i.e. single-site, catalysis and may comprise a variety ofmonomers, including but not limited to propylene, ethylene, 1-butene,octene and hexene. Common thermoplastic polyolefin elastomers includefor example amorphous (atactic) propylene (APP), propylene-ethylenecopolymers, ethylene-octene copolymers, propylene-1-butene copolymers,propylene-hexene copolymers, propylene-ethylene-1-butene copolymers.Polyolefins produced by metallocene catalysis may have higher comonomerincorporation when compared to polymers produced by Ziegler-Nattacatalysis. Examples of polymers suitable for polyolefin-based adhesiveinclude for example Vestoplast®, Infuse®, Affinity® and Vistamaxx®polymers.

Tackifiers are compounds that may be used in adhesives for increasingtack, i.e. stickiness of the adhesive. Tackifiers are typically lowmolecular weight compounds, and their glass transition and softeningtemperatures are typically above room temperature. Tackifiers aretypically chosen based on base polymer compatibility and desiredproperties of the end product. Tackifiers are typically resins, such asrosins and their derivatives, terpenes and modified terpenes,terpene-phenol resins, phenol resins, or hydrocarbon resins. Hydrocarbonresin (HC) may be partially hydrogenated or fully hydrogenated.Hydrocarbon resin may be aliphatic or aromatic resin. Hydrocarbon resinmay be based on aliphatic HC comprising five carbons (C₅) and/oraromatic HC comprising nine carbons (C₉). Within context of thisspecification, hydrocarbon resin based on aliphatic HC comprising fivecarbons also includes dicyclopentadiene (DCPD). DCPD may dissociate tocyclopentadiene (C₅) monomer.

Plasticizers are compounds that may decrease plasticity or viscosity ofa material. Plasticizers thus are substances that may be added in orderto alter physical properties of the materials. Plasticizer may decreasethe attraction between polymer chains in order to make them moreflexible. Plasticizers are an important component of many adhesives.Plasticizers may lower the glass transition temperature and elasticmodulus of an adhesive. Plasticizers are typically chosen based on basepolymer compatibility and desired properties of the end product. Bychoosing a plasticizer that is compatible with the base polymer, theplasticizer may be protected for leaching out of the product and thuslosing benefits of plasticization.

Besides the base polymer, tackifier and plasticizer the adhesive maycomprise any conventional adhesive component(s), such as antioxidant(s),filler(s) and/or wax(es).

An important property for the adhesive of a recyclable label is that itscomponents show chemical compatibility, in particular with each otherbut also with the packaging material to be recycled with. Chemicalcompatibility of the adhesive components ensure uniform phase structure,thus decreasing haze. Another important aspect is that the adhesive doesnot cause undesired odour or smell to the recycled material. Further, itshould exhibit UV stability during shelf-life of the package. Also, itis of importance that the adhesive shows heat stability during therecycling process, and occurrence of burned particles and/ordiscoloration, or odour formation are avoided.

According to an embodiment, an adhesive for a recyclable label comprisesa base polymer, a tackifier and a plasticizer. The adhesive is apressure sensitive adhesive. The pressure sensitive adhesive may be awater-based adhesive, a solvent-based adhesive or a hot melt adhesive.

According to an embodiment, the pressure sensitive adhesive disclosedherein is a hot melt adhesive.

The adhesive components, i.e. the base polymer, the tackifier and theplasticizer are colourless and odourless. The adhesive components arecolourless and odourless each of them separately as well as whencombined in order to provide the adhesive. Further, the adhesivecomponents are colourless and odourless during and after the recyclingprocess. Within context of this specification colourless refers to aproperty of having no colour sensible to a human eye. Colourless mayalso comprise transparent or translucent features. Within context ofthis specification odour is caused by one or more volatilized chemicalcompounds, i.e. volatiles, that are found in concentrations that humansand animals can perceive by their sense of smell. Thus, odourlesscomponent refers to a component that does not comprise significantamount of volatiles. Term “volatile” refers to a substance thatvaporizes readily. A volatile substance has a high vapor pressure at agiven temperature compared with a non-volatile compound. The higher thevapor pressure of a compound, the more volatile it is. Higher vaporpressure and volatility translate into a lower boiling point. Increasingtemperature increases vapor pressure, which is the pressure at which thegas phase is in equilibrium with the liquid or solid phase.

In order to obtain above described stability demands placed for theadhesive, the adhesive components should show stability. Thus, it isbeneficial that the components comprise as low amount of reactivefunctional groups, such as double bonds, as possible. For example,adhesive components comprising reactive double bonds are prone toyellowing, thus causing undesired colour to the adhesive and/or to therecycled plastic material. Reactive adhesive components may also beprone to cause odour or smell when degraded/reacted.

The amount of base polymer in the adhesive is at least 15 wt. %. Theamount of base polymer may be from 15 to 50 wt. %, preferably from 20 to40 wt. %.

According to an embodiment, the base polymer is a polyolefin. Polyolefinmay comprise a variety of monomers, including but not limited toethylene, propylene, 1-butene, octene, hexene. Polyolefin may be forexample amorphous (atactic) propylene (APP), propylene-ethylenecopolymer, ethylene-octene copolymer, propylene-1-butene copolymer,propylene-hexene copolymer, propylene-ethylene-1-butene copolymer.

In order to increase the compatibility of the base polymer of the hotmelt adhesive with packaging material comprising ethylene containingpolymer in the recycled plastic material it may be beneficial that thebase polymer contains ethylene. The base polymer may be a copolymercontaining ethylene monomer(s).

The amount of tackifier in the adhesive is at least 25 wt. %. The amountof tackifier may be from 25 to 60 wt. %, preferably from 40 to 50 wt. %.

According to an embodiment, the tackifier is partially or fullyhydrogenated hydrocarbon resin. The hydrocarbon resin may be for exampleC₅/C₉ resin, C₅ resin, or C₉ resin.

The amount of plasticizer in the adhesive is at least 10 wt. %. Theamount of plasticizer may be from 10 to 50 wt. %, preferably from 10 to25 wt. % or from 20 to 50 wt. %.

The plasticizer may comprise an average molecular weight of at least 480Da. Additionally or alternatively, the plasticizer may have a viscosityat 100 degrees C. of at least 8.5 cSt (8.5×10⁻⁶ m²/s). Additionally oralternatively, the plasticizer may have a content of mineralhydrocarbons with a carbon number equal to or below 25 of not more than5% (w/w). The plasticizer may be a mineral oil. The mineral oil may bederived from petroleum based hydrocarbon feedstocks. The mineral oilsmay comprise for example white oils, paraffinic oils, naphthenic oils.Other suitable plasticizers may comprise for example adipates,polypropylene oligomers, polybutene oligomers, polyisoprene oligomers,hydrogenated polyisoprene and/or polybutadiene oligomers, benzoateesters, vegetable or animal oils and their derivatives, sulfonic acidesters, mono or polyhydric alcohols, polyalkylene glycols having amolecular weight of from 200 to 6000 g/mol, such as polypropylene glycolor polybutylene glycol. The plasticizer component is preferably liquidat room temperature.

According to an embodiment, the hot melt adhesive comprises at least 15wt. % of a base polymer, at least 25 wt. % of a tackifier and at least10 wt. % of a plasticizer. The base polymer, the tackifier and theplasticizer are colourless and odourless. The base polymer isethylene-octene copolymer. The tackifier is hydrogenated hydrocarbon.The plasticizer comprises a compound fulfilling at least one of thefollowing: comprising an average molecular weight of at least 480 Da,having a viscosity at 100 degrees C. of at least 8.5×10⁻⁶ m²/s, having acontent of mineral hydrocarbons with a carbon number equal to or below25 of not more than 5% (w/w).

In an example, the hydrogenated hydrocarbon as a tackifier iscycloaliphatic hydrocarbon resin, for example dicyclopentadiene (DCPD).

Packaging Material

Within context of this specification the packaging material, i.e. thematerial of an item 100, comprises ethylene containing polymer. Theethylene containing polymer refers to a polymer that comprises ethyleneas a monomer unit. The ethylene containing polymer may refer topolyethylene, a copolymer containing ethylene, or polyethylene mixedwith other polymer. The package, i.e. the item 100, may be flexible orrigid. The package may be printed or nonprinted.

According to an embodiment the packaging material comprises HDPE.

According to an embodiment the packaging material comprises copolymer ofpropylene and ethylene.

According to an embodiment the package is a bottle. The bottle may befor example a bottle for a home care or personal care product. Accordingto another embodiment the package is a flexible package.

Recycling Process

Labels according to this disclosure are intended to be recycledmechanically. An exemplary mechanical recycling process is illustratedin FIG. 4 . In a mechanical recycling process the labelled packaging maybe first pre-treated. In the pre-treatment step 421 the labelledpackaging may be exposed to a preliminary washing and/or sorting. Thelabelled packaging is typically shredded in the pre-treatment step. Thefollowing step, i.e. a mixing and heating step comprises heating andmixing of the (shredded) materials. The heated and mixed materials maybe extruded in order to provide a melt stream. The melt stream may thenbe filtered and degassed. In the final, pelletizing step 423 the meltstream may be pelletized so as to produce recycled plastics as anoutput.

An apparatus for mechanical recycling typically comprises a feedingdevice for feeding the material to be recycled and a cutter-compactorfor cutting, mixing, heating, drying, pre-compacting and buffering thematerial. After the cutter-compactor an extruder screw may be arrangedfor providing the melt stream. The extruder screw may comprise a filter,a homogenization zone, a degassing zone and a discharge zone. After theextruder screw, a pelletizer may be provided for producing pellets fromthe recycled material.

It is of importance that the label materials show stability in therecycling process. Thus, the recycling process itself may not causeunwanted properties to the recycled material. For example heat stabilityduring the recycling process is needed in order to avoid burnedparticles and/or discoloration, or smell created by degradation thatmight compromise the quality of the recycled plastic.

It is also beneficial that the label materials are such that they do notcontaminate the recycling apparatus.

Besides labels, also the so-called waste matrix obtained as a result ofconversion of the labels disclosed herein can be recycled mechanically.Waste matrix refers to the material between and around each label. Thus,the waste matrix comprises the same components as the label, i.e. theface and the adhesive, as discussed above. The waste matrix is formed bydie or kiss cutting the labels from the label laminate and may bestripped away subsequently, preferably immediately, after the cuttingaction as a continuous waste matrix skeleton. The waste matrix skeletonmay also be called waste matrix web. Conventionally the waste matrix isreeled up and removed for disposal as solid waste or used as fuel. Moresustainable alternatives for disposal as solid waste or for combustinghave been studied.

Mechanical recycling and reuse of thus formed recycled plastic providesa sustainable approach for the waste matrix treatment. The recycledfraction comprising waste matrix may have an adhesive content of even upto 20 wt. %, for example 15 wt. %. The waste matrix having the facecomprising ethylene containing polymer and the adhesive disclosed hereineven at such high contents is suitable for recycling and for providingrecycled plastic. The waste matrix may be recycled such that therecycled fraction consists of the waste matrix, i.e. there is no othermaterial included besides the waste matrix to be recycled.

The recycled fraction comprising waste matrix may be treated asdiscussed above to produce granulates of recycled plastic. Granulatesmay also be called pellets. The produced granulates may be used forexample for polyethylene extrusion. As the recycled fraction comprisingwaste matrix has higher adhesive content and comprises smaller moleculeswhen compared to one comprising labelled packages, the mechanicalproperties of the products prepared from the granulates thereof may besomewhat weaker. However, the granulates of recycled plastic thusprepared may be mixed with ones having better properties, thus leadingto recycled plastic with comparable mechanical properties. The amount ofthe granulates as well as the counterpart material may be tunedaccording to the application in question.

A circular economy approach towards waste elimination and continual useof resources is provided by mechanical recycling of the waste matrixdisclosed herein as well as use of the recycled plastic thus formed.

Properties of the Recycled Material

As already mentioned, the label must not compromise quality of therecycled fraction. In particular, the adhesive of the label must notcompromise quality of the recycled fraction. Quality of the recycledfraction may refer for example to odour, colour, processability,mechanical properties, and/or optical properties. It is important thatthe adhesive is compatible with other components of the recycledfraction. It may be estimated that the recycled plastic containing thelabel and the packaging material comprises at maximum 5% (by weight)adhesive.

Compatibility of the adhesive may be detected for example by visualaspects (such as haze, gloss and/or colour), microscopy analyses forphase structure and DSC analyses of the recycled plastic comprising theadhesive.

Morphology or phase structure of the recycled material may be inspectedby microscopy, such as light microscopy or scanning electron microscopy(SEM).

With a light microscope, i.e. optical microscope, changes in themorphology or phase structure of the material caused by incompatiblecomponents are clearly visible in film cross section samples preparedwith a diamond knife, as illustrated in FIGS. 5 and 6 and discussed inthe Test experiments section.

Colour of the recycled plastic may be determined using a so-calledCIELAB colour space, which expresses colour as three values: L* for thelightness from black (0) to white (100), a* from green (−) to red (+),and b* from blue (−) to yellow (+). The colour values may be measuredaccording to an ISO 5631 standard. The b* value describing theyellowness is relevant in determining quality of the recycled plastic.The higher the b* value, the yellower the sample is.

Haze is a property that is measured as the percentage of incident lightscattered by more than 2.5° through a plastic sample. The lower the hazevalue, the higher the clarity. Impurities contained in the plasticmaterial, inhomogenities as well as mechanical and chemical degradationare among the factors that may be responsible for light scattering andthus higher haze value. Incompatible components, i.e. components that donot show chemical compatibility and/or recycling compatibility, maycause different phases to form into the material. Haze arises fromphases having difference in their refractive indexes causing scatteringof light on the phase interfaces. Haze is tested according to a standardASTM D1003. Haze of a sample may be measured with an instrumentconforming to the requirements of ASTM D1003 Section 8: Procedure BSpectrophotometer.

Gloss is an important optical property associated with plastics surfaceand it is defined as the capacity of the polymer surface to reflectlight in a given direction. Gloss characterizes how reflective or shinya plastic material is, i.e. how much of a light beam touching thematerial with a defined incident angle is reflected vs. a standardmaterial (a black specimen with a defined refractive index=100). A highgloss will produce a sharp image of any light source and thus will giverise to a pleasing sparkle on the surface. Materials having a high glossare very smooth and highly reflective.

For the adhesive to be compatible with the components of the recycledfraction, the mechanical properties of the recycled plastic should notsubstantially deviate from the properties of a recycled plastic notcontaining the adhesive. The mechanical properties include for exampleelongation at break and tensile strength. Elongation at break, alsoknown as fracture strain or tensile elongation at break, is related toability of a plastic material sample to resist changes of shape withoutcracking. Elongation at break is a ratio between increased length andinitial length after breakage of the tested sample at a controlledtemperature. Tensile strength, for one, refers to a maximum stress thata material can withstand while being stretched or pulled beforebreaking. Tensile strength is a stress measured as force per unit area.Tensile strength may also be referred to as ultimate tensile strength,or ultimate strength.

Further, the processability of the recycled plastic should be comparableto the non-recycled plastic. The processability may for example relateto melt flow rate (MFR) or behaviour in film/bottle/containermanufacturing. The processability of the recycled plastic refers to theprocessability for example in film extrusion, injection moulding etc.The melt flow rate is a measure of the ease of flow of the melt of athermoplastic polymer.

Finally, it is of importance that the adhesive is compatible with othercomponents of the recycled fraction such that it does not cause unwantedsmell to the recycled plastic. On one hand the adhesive itself shouldnot produce unwanted smell, i.e. the components should not containsignificant amount of volatiles. On the other hand the adhesive shouldnot be degraded during the recycling process and cause odour or smell.

Test Experiments

In the first experiment, compatibility of different types ofcommercially available adhesives with plastic packaging materials wasinvestigated. As the material representing packaging material, a clear,one-layer blown film made of MDPE was used. The samples were prepared byadding 5% of different types of adhesives at a time to the MDPE polymer.An adhesive dosing of 5% (by weight) was chosen based on the hypothesisthat said amount represents the maximum realistic total adhesive amountin packaging waste stream. A reference sample contained only MDPE, noadhesive. The samples thus prepared were exposed to a mechanicalrecycling process simulating the process described above. In the firststep the materials were processed through a cylindrical extruder inorder to compact/melt the different streams of adhesive and film to onematerial stream. The second step comprised grinding of the compactedtest materials. In the third step a cast film having a thickness of500-700 μm was casted using a small scale extruder. The properties ofthe films thus prepared were studied. On the basis of the experiments,hot melt adhesive was shown to be superior in compatibility with PEpolymer to acrylate based adhesive. This is illustrated in FIG. 5showing optical microscope images (100× magnification) of the samplesprepared. The reference sample 1 containing only PE material as well asthe sample 2 (PE+5% of a hot melt adhesive) are shown to consist of auniform, nicely transparent phase. In images of samples 3 and 4containing PE and 5% of two different acrylic adhesives the phasestructure is shown to be far less uniform.

In the second experiment, compatibility of different components of hotmelt adhesive with the packaging material was investigated. The aim wasoptimize the components in order to provide a hot melt adhesive thatwould be as compatible as possible with the PE packaging material.Results are illustrated in Table 1. As the material representingpolyethylene packaging material HDPE pellets were used. The samples wereprepared by adding 15% (by weight) of one adhesive component at a timeto the HDPE polymer by a mini-compounder. Reference sample 1 containedno adhesive component. Reference samples 2 and 3 contained commerciallyavailable hot melt and acrylic adhesives, respectively. A coin having adiameter of 25 mm and thickness of 1 mm was injection moulded from thematerials mixture and colour (V value) and haze (%) of the coin sampleswere inspected. Colour and haze were measured by a Hunterlab UltrascanVIS spectrophotometer. Colour values were measured using setting D65/10°simulating daylight conditions. Based on the experiments, a general rulemay be derived, according to which a haze difference of 1%-unit is notvisually observable, whereas a difference of 3%-units may be observedvisually. Odour of the samples was also detected. Reference sample 2(commercially available hot melt adhesive) and sample 2 (SBR) weredetected to possess odour that was not satisfying the quality demandsplaced for recycled plastic material. Other samples were shown not topossess odour or were shown to possess only minor odour, Opticalmicroscope images of certain samples are shown in FIG. 6 , Image Aillustrates reference sample 1 of Table 1, i.e. the HDPE polymer with noadhesive component. Image B illustrates sample 1 (HDPE+SIS), image Csample 2 (HDPE+SBR), image D sample 3 (HDPE+SEBS), image E sample 4(HDPE+amorphous poly-alpha olefin) and image F sample 5(HDPE+ethylene-octene copolymer), respectively. Images clearly show thataddition of SIS, SEBS or ethylene-octene copolymer to HDPE has nosignificant effect on the phase structure. Thus, said components appearto be chemically compatible with HDPE. Addition of SBR or the amorphouspoly-alpha olefin tested, for one, clearly show a difference in thephase structure when compared to reference HDPE material, thusindicating their chemical incompatibility with HDPE.

Base polymers SIS, SEES and ethylene-octene copolymer (samples 1, 3 and5, respectively), as well as tackifiers C5/C9 resin 2, partiallyhydrogenated (PH) C5/C9 resin and fully hydrogenated (FH) C5 resin(samples 7, 8 and 9, respectively) were, of the tested components, underthe test conditions, shown to be the most compatible with HDPE. Of thetested components, all plasticizers were under the test conditions shownto be more or less compatible with HDPE. Plasticizers 13 and 14 showed aslight odour, whereas plasticizers 15, 16 and 17 in practice showed noodour.

TABLE 1 Adhesive Sample Polymer Type component Colour Haze REF HDPE 6.0394.80 REF2 HDPE HM RH1S Hot melt adhesive 16.14 93.96 REF3 HDPE WB RP37Acrylic adhesive 14.76 97.52 1 HDPE Base polymer SIS 7.64 95.30 2 HDPEBase polymer SBR 9.97 94.40 3 HDPE Base polymer SEBS 6.52 94.66 4 HDPEBase polymer Amorphous poly- 8.96 97.54 alpha olefin 5 HDPE Base polymerethylene-octene 7.74 93.90 copolymer 6 HDPE Tackifier C5/C9 resin 110.89 95.18 7 HDPE Tackifier C5/C9 resin 2 9.02 94.54 8 HDPE TackifierPH C5/C9 resin 6.49 94.26 9 HDPE Tackifier FH C5 resin 6.08 94.22 10HDPE Tackifier C5 resin 10.25 93.80 11 HDPE Tackifier Rosin ester resin13.84 93.64 12 HDPE Tackifier Hydrogen. rosin 11.30 94.28 ester resin 13HDPE Plasticizer Mineral oil 5.76 92.30 14 HDPE Plasticizer Low MW PIB6.31 91.04 15 HDPE Plasticizer High MW PIB 6.88 94.96 16 HDPEPlasticizer Pharma oil 7.55 92.14 17 HDPE Plasticizer High MW pharma6.43 91.68 oil

1. A mechanically recyclable label (1) for mechanical recycling withpackaging material the label has been adhered to, the packaging materialcomprising ethylene containing polymer, the mechanically recyclablelabel (1) comprising a face (2) and an adhesive (4), wherein the face(2) comprises ethylene containing polymer and the adhesive (4) comprisespressure sensitive adhesive, the pressure sensitive adhesive comprising20-40 wt. % of a base polymer, at least 25 wt. % of a tackifier and atleast 10 wt. % of a plasticizer, and wherein the base polymer isethylene-octene copolymer and the tackifier is hydrogenated hydrocarbonresin.
 2. (canceled)
 3. The mechanically recyclable label (1) accordingto claim wherein the plasticizer comprises a compound fulfilling atleast one of the following: comprising an average molecular weight of atleast 480 Da, having a viscosity at 100 degrees C. of at least 8.5×10⁻⁶m²/s, having a content of mineral hydrocarbons with a carbon numberequal to or below 25 of not more than 5% (w/w).
 4. The mechanicallyrecyclable label (1) according to claim 1, wherein the label (1) ismechanically recyclable in a process comprising ethylene containingpolymer and at most 5 wt. % of pressure sensitive adhesive, the processbeing arranged to provide recycled plastic material.
 5. The mechanicallyrecyclable label (1) according to claim 1, wherein the tackifier is atleast one of the following: C₅/C₉ resin, C₅ resin, C₉ resin.
 6. A labellaminate (8) for providing mechanically recyclable labels (1) formechanical recycling with packaging material the label has been adheredto, the packaging material comprising ethylene containing polymer, thelabel laminate (8) comprising a face (2), an adhesive (4) and a releaseliner (6), the face (2) being adjoined to the release liner (6) via theadhesive (4), the face (2) comprising ethylene containing polymer andthe adhesive (4) comprising pressure sensitive adhesive, the pressuresensitive adhesive comprising 20-40 wt. % of a base polymer, at least 25wt. % of a tackifier and at least 10 wt. % of a plasticizer, and whereinthe base polymer is ethylene-octene copolymer and the tackifier ishydrogenated hydrocarbon resin.
 7. (canceled)
 8. The label laminate (8)according to claim 6, wherein the plasticizer comprises a compoundfulfilling at least one of the following: comprising an averagemolecular weight of at least 480 Da, having a viscosity at 100 degreesC. of at least 8.5×10⁻⁶ m²/s, having a content of mineral hydrocarbonswith a carbon number equal to or below 25 of not more than 5% (w/w). 9.The label laminate (8) according to claim 6, wherein the tackifier is atleast one of the following: C₅/C₉ resin, C₅ resin, C₉ resin.
 10. Amethod for manufacturing a label laminate (8) according to claim 6, themethod comprising the following steps of: arranging a substrate as arelease liner (6) or a face (2), coating the substrate with an adhesive(4), the adhesive (4) comprising pressure sensitive adhesive, andlaminating the release liner (6) together with the face (2) in such away that the adhesive (4) is arranged in between the face (2) and therelease liner (6), wherein the face (2) comprises ethylene containingpolymer and the pressure sensitive adhesive comprises at least 15 wt. %of a base polymer, at least 25 wt. % of a tackifier and at least 10 wt.% of a plasticizer, and wherein the base polymer, the tackifier and theplasticizer are colourless and odourless, and wherein the base polymeris a ethylene-octene copolymer and the tackifier is hydrogenatedhydrocarbon resin.
 11. A labelled item (101) comprising an item (100)and a mechanically recyclable label (1) according to claim 1, whereinthe mechanically recyclable label (1) is attached to a surface of theitem (100) through the adhesive (4) of the label (1), the material ofthe item comprises ethylene containing polymer, and the labelled item ismechanically recyclable.
 12. Use of a mechanically recyclable label (1)according to claim 1 for labelling an item (100).
 13. Use of a labellaminate (8) according to claim 6 for providing mechanically recyclablelabels (1).
 14. Use of a waste matrix of a label laminate (8) accordingto claim 6 for producing granulates of recycled plastic, wherein thewaste matrix comprises a face (2) and an adhesive (4).
 15. A granulateof recycled plastic, comprising a waste matrix of a label laminate (8)according to claim 6, wherein the waste matrix comprises a face (2) andan adhesive (4).
 16. Use of a granulate according to claim 15 forproviding a plastic item.
 17. A plastic item comprising a granulate ofrecycled plastic according to claim 15.